Many search engines and online retail aggregators populate databases of advertisements by receiving descriptions of all the products the online retailer has for sale. This operation puts the burden on the online retailer to make the data available in formats that the search engines or retail aggregators may use. Such a burden is costly for the retailer and may have to be duplicated for each search engine and retail aggregator that the retailer may desire to use. In many cases, the retailer's data may change often, such as when price changes occur or when inventory levels change.